Jiang et al. (2025) Spatial and temporal variation of raindrop size distribution in Great Britain

Identification

• Journal: Atmospheric Research
• Year: 2025
• Date: 2025-12-11
• Authors: Shan Jiang, Dawei Han, Rafael Rosolem, Merhala Thurai, Miguel A. Rico‐Ramirez
• DOI: 10.1016/j.atmosres.2025.108699

Research Groups

• School of Civil, Aerospace and Design Engineering, University of Bristol, Bristol, UK
• Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, USA

Short Summary

This study investigates the spatial and temporal characteristics of raindrop size distributions (DSDs) across Great Britain using disdrometer data from 2017-2019. It reveals distinct geographical and topographical influences on DSD parameters, significant differences between stratiform and convective rain types, and unique seasonal variations in extreme convective events compared to subtropical/tropical regions.

Objective

• To understand how DSD parameters change across different seasons in Great Britain (GB).
• To analyze how DSD parameters vary spatially across various locations in GB.
• To compare GB's DSD parameters with those observed in other regions globally.

Study Configuration

• Spatial Scale: Great Britain, utilizing data from eleven Thies laser precipitation monitors (LPMs) distributed across various geographical and topographical regions.
• Temporal Scale: Three years, from 2017 to 2019, ensuring comprehensive seasonal coverage.

Methodology and Data

• Models used: Normalized gamma drop distribution model was fitted to approximately one million one-minute raindrop samples.
• Data sources:
  • Eleven Thies laser precipitation monitors (LPMs) from the Disdrometer Verification Network (DiVeN).
  • Tipping bucket rain gauges (TBRGs) from the Met Office’s land surface and marine surface measurements dataset for quality control and outlier removal.

Main Results

• The average mass-weighted mean diameter (〈Dm〉) and the average normalized intercept parameter (log10〈Nw〉) are significantly influenced by geographical and atmospheric conditions.
• Western and hilly regions exhibit lower 〈Dm〉 and higher log10〈Nw〉, while the eastern plain of GB shows the opposite pattern.
• Both 〈Dm〉 and log10〈Nw〉 are strongly correlated with rain rate, with heavier rain rates generally associated with larger 〈Dm〉 and smaller log10〈Nw〉.
• Stratiform rain in GB is characterized by smaller 〈Dm〉 (0.78–1.00 mm) and larger log10〈Nw〉 (3.82–4.41) compared to subtropical/tropical regions.
• Convective rain in GB shows larger 〈Dm〉 (1.30–1.74 mm) and log10〈Nw〉 (3.63–4.21), aligning with the maritime-like cluster.
• Both stratiform and convective rain exhibit a significant negative linear correlation between 〈Dm〉 and log10〈Nw〉 (Pearson correlation coefficients of -0.95 and -0.98, respectively).
• Extreme convective events display distinct seasonality, with larger Dm and lower log10(Nw) during the warm season compared to the cold season.
• A bimodal distribution for log10(Nw) is observed in light rain events over western and hilly regions, indicating complex microphysical processes for small raindrops.

Contributions

• Provides a comprehensive understanding of the spatiotemporal characteristics of DSDs in a mid-latitude temperate maritime island country (Great Britain), addressing a gap in existing literature.
• Offers valuable insights into precipitation formation processes in GB, considering different rain types, seasons, and geographical/topographical influences.
• Contributes to improving quantitative precipitation estimation (QPE) algorithms for weather radar applications in GB.

Funding

• China Scholarship Council and the University of Bristol (joint scholarship CSC No. 202408420031).
• MOSAIC project (grant No. NE/T005645/1).
• COSMIC-SWAMP project (grant No. NE/W004364/1).
• US National Science Foundation (award number 2418753) for M. Thurai.

Citation

@article{Jiang2025Spatial,
  author = {Jiang, Shan and Han, Dawei and Rosolem, Rafael and Thurai, Merhala and Rico‐Ramirez, Miguel A.},
  title = {Spatial and temporal variation of raindrop size distribution in Great Britain},
  journal = {Atmospheric Research},
  year = {2025},
  doi = {10.1016/j.atmosres.2025.108699},
  url = {https://doi.org/10.1016/j.atmosres.2025.108699}
}